The present invention relates to a method for vascular embolization or, more particularly, to a method for vascular embolization in which a liquid embolizing agent, which can be coagulated at the body temperature, is introduced into the blood vessel of a patient so as to prevent bleeding from the open end of the blood vessel or to facilitate cure of disordered blood vessel without undertaking a surgical procedure with embolization of the disordered blood vessel by the subsequent coagulation of the embolizing agent.
As a consequence of the remarkable progress in the medical science and technology in recent years, intravascular surgery is now frequently undertaken as a therapeutic means from inside of blood vessels as an application of the radiological technology for angiography. In conducting such intravascular surgery, it is essential to establish a means for the vascular embolization using a vascular embolizing agent by which the blood vessel to be subjected to the surgery is embolized to prevent bleeding from the open end thereof. Further, it is expected that the disordered blood vessel can be cured without undertaking ordinary surgical procedure by embolizing the disordered blood vessel.
A vascular embolizing agent above mentioned, which is a liquid capable of being coagulated or converted into a non-flowable mass after injection into the blood vessel of the patient, must satisfy several requirements, i.e., that it be a liquid suitable for smooth injection into blood vessels without difficulty, that the length of time taken for coagulation in the blood vessel of a living body can be controlled within a wide range, that it be stable in and non-toxic against human body, that it can withstand a sterilization treatment without causing denaturation, that the coagulate of the agent can be re-dissolved, for example, in the event of inadvertent trouble due to embolization of a normal blood vessel to regain blood circulation, that it be opaque to X-rays in order to facilitate detection of the location where vascular embolization has taken place and so on. However, no vascular embolizing agent is available which can satisfy all of these requirements.
For example, vascular embolizing agents heretofore known include a polymerizable monomeric compound such as n-butyl cyanoacrylate which can be converted into a polymer after being injected into the blood vessel of a patient and a solution of a polymer in an organic solvent, such as ethyl alcohol and dimethyl sulfoxide, from which, when injected into a blood vessel, the solvent is absorbed by diffusion into the tissue of the blood vessel to leave the polymeric material. Examples of the polymer suitable for this purpose include copolymers consisting of ethylene and vinyl alcohol moieties soluble in dimethyl sulfoxide, polyvinyl acetate soluble in ethyl alcohol, a commercial product sold under a tradename of Eudragit (copolymer of (meth) acrylic monomers, a product by Rohm Pharma Co., Germany) soluble in ethyl alcohol and so on.
The above mentioned butyl cyanoacrylate acts as an adhesive when it is polymerized so that the use thereof as a vascular embolizing agent involves a risk of complications to the patient. The solution-type agents of the latter class are unavoidably accompanied by troubles due to absorption of the organic solvent in the living body. For example, ethyl alcohol is liable to cause dermatopathy within the blood vessel and dimethyl sulfoxide has a problem of, besides the physiological effects on the living body, solubility to various polymers so that catheters of a certain polymer are dissolved by the dimethyl sulfoxide solution.
Thus, the liquid vascular embolizing agents heretofore proposed are each not free from the disadvantages due to the risk of very harmful side effects and the various troubles for which the organic solvents are responsible.